West Nile Virus
With Brooke Shadel
Associate Director, Center for the
Study of Emerging Infections,
Saint Louis University
Friday, Aug. 9, 2002; 3 p.m. EDT

District of Columbia health officials said Wednesday that a Washington man has contracted the mosquito-borne West Nile virus, the first confirmed human case of the disease in the region this year. The city's announcement came as officials across the country are battling the worst outbreak of West Nile virus since it was detected in the U.S. in 1999.

Professor Brooke Shadel, associate director of the Center for the Study of Emerging Infections at Saint Louis University, was online Friday, Aug. 9 at 3 p.m. EDT, to discuss the West Nile virus, its public health implications, how the disease is transmitted, steps people can take to avoid getting it and the symptoms and risks associated with it.

The transcript follows.

Editor's Note: Washingtonpost.com moderators retain editorial control over Live Online discussions and choose the most relevant questions for guests and hosts; guests and hosts can decline to answer questions.

Brooke Shadel: Looking forward to your questions today.

St. Louis, Mo.: I am a woman who is eight weeks pregnant. I know of the devasting effects cytomegalovirus (CMV) can have on an unborn child. Are the effects of the West Nile virus on a fetus known?

Brooke Shadel: Pregnant women are not known to be at higher risk for infection with the West Nile Virus. Of the cases in the United States thus far there is not enough data to know the effects of infection on the fetus. Pregnant women should take the same precautions as other people.

St. Louis, Mo.: How does a person contract the disease? Are there steps to prevent contracting it, and are there remedies to combat the illness once it is contracted?

Are children at greater risk than adults?

Brooke Shadel: A person contracts the disease by a bite from an infected mosquito. Prevention occurs in two ways both community wide and steps an individual can take. Health departments will apply appropriate control measures to control the mosquito population. Personal protective measures include avoid mosquito bites by staying in during dusk and dawn, using insect repellant that contain DEET. The elderly and the immunocompromised are at greater risk for severe disease. Even though children may get infected as other adults they seem to be less likely to have severe disease from the cases so far.

Washington, D.C.: What are some of the symptoms for D.C. residents to look for? Does West Nile virus affect children the same as adults? What distinguishes the West Nile virus from the flu -- what makes it strong enough to kill?

Brooke Shadel: The symptoms vary, but 80% of the people infected have no symptoms at all. Approximately 20% may have a mild illness with fevers and body aches somewhat similar to the flu. Less than 1 in 100 of people infected develop more severe symptoms including confusion, coma, muscle weakness (symptoms of encephalitis) or sever headaches, neck stiffness (menigitis). In severe cases the infection of the brain leads to paralysis and death.

Vienna, Va.: Ms. Shadel -- I have read that once bitten by a mosquito that is infected with West Nile certain human beings will not become ill and in fact will become immune to the disease. True?

Brooke Shadel: 80% of people who become infected do not become ill. Infection may lead to immunity versus further infection. The duration of the immunity could be lifelong. This issue needs to be studied further.

Philadelphia, Pa.: Hi,

My grandmother lives in Capital Heights, Md, zip 20743 and three neighbors in one day spotted a dead crow in their respective yards or areas. The crows have not been picked up by the authorities. My concern is that three in one small area in one day seems awfully high. Is there more to this and how can she get the authorities to come out and pick them up?

Brooke Shadel: There are two ways to dispose of the birds. Your grandmother could call the local health department and ask if they would remove the dead birds from the yard or instructions of how to dispose of the birds. To date there has not been any human to animal transmission.

St. Louis, Mo.: For those people who do get symptoms, what is the time period from the time of when they possibly received the mosquito bite till they start having symptoms?

Brooke Shadel: The incubation period is approximately 3 to 15 days. So people that are infected and develop symptoms will start to notice the effects in 3 to 15 days.

St. Louis, Mo.: I've heard there is a vaccine for the virus. Why isn't more being done in the way of prevention? I've also heard it is possible that states might pay for the vaccine, when would this happen?

Brooke Shadel: Vaccines are being developed for humans, but none are approved for use. There is a vaccine for horses.

Laurel, Md.: I get bitten a lot. Is there a test to see if you have been exposed? Or is that not necessary for an otherwise healthy person?

Brooke Shadel: Yes, there is a test to confirm exposure. We use the tests to identify cases for epidemiological reasons to track the disease. Tests to confirm exposure are not needed for individuals who do not develop symtoms.

Boston, Mass.: If more than 80% of those infected never develop symptoms, how would you know if you've been infected?

Brooke Shadel: You would not know unless symptoms developed.

Washington, D.C.: What kind of mosquitos carry West Nile? The new tiger mosquito, native ones or all of them?

Brooke Shadel: The primary mosquitoes that carry the West Nile virus are of the Culex species, which primarily bite birds. However, as viral activity increases in an area other mosquito species can also transmit the infection including species that prefer feeding on humans.

Georgetown: Does West Nile show up in birds other than crows? The reason I ask is that I had a dead chickadee in my garden the other day -- which I attributed to the homicidal cat next door. Any chance it was instead claimed by the disease?

Also, we have a nasy Asian mosquito problem. What are these "tablets" that you can put in water to kill the larvae? Are they the same as the round doughnut-shaped dunks?

Brooke Shadel: Other bird species can become infected particulary blue jays, however American Crows are the most common. Lavicidal agents can come in tablet forms and are added to stagnet water pools to kill mosquito larvae before they can become biting adults.

Brooke Shadel: I appreciate the opportunity to answer your questions. The lessons we have learned from this outbreak of West Nile Virus stress the importance of maintaining and augmenting our public health infrastructure and provides an opportunity for institutions both public and private to work together to prevent disease.

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